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Thread: BB for balancing tires. legit ?

  1. #1
    Senior Member bellwilliam's Avatar
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    Default BB for balancing tires. legit ?

    using bb's to balance tires. Trackhq engineers, chime in please.

    rule of thumb is to use 1oz of BB for every 10-13LB of tires.
    there is a company, dynabead. that sells tiny bb that goes down the stem. or you can just use regular airgun bb.
    it also works on "narrower" tires better than "wider" tires


    Last edited by bellwilliam; 07-12-2017 at 10:47 AM.
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    Senior Member bellwilliam's Avatar
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    someone on internet posted this, so this must be true ?

    The Physics:

    Tire at Rest: The beads rest on the tire floor due to gravity.
    Tire in Motion: The beads distribute uniformly by friction as the tire begins to rotate, where they are held in place by centrifugal force (F=m*v^2/r), acting perpendicular to the tire wall. Note that beads would remain in this state for a perfectly balanced tire. For completeness, gravity still acts on the beads but is small relative to centrifugal forces.
    Heavy Spots in Tire: In this time step it is important to remember that the vehicle's suspension allows the wheel assembly to move vertically- Upward motion is resisted by the car's suspension (spring) while downward motion is assisted by the suspension (spring) and resisted by tire pressure against the roadbed. As the 'heavy spots' in the tire are rotated at higher velocities, their centrifugal (inertial) forces physically move the tire up and down- poorly balanced tires can literally cause 'wheel hop'! As the tire moves (up and down), the beads, with their own masses resisting motion, do not move rigidly with the tire's translation; they move relative to the tire. Note that without vertical movements, only centrifugal forces act on the beads and they maintain their new position on the tire wall.
    Imagine a bead when the tire moves up (ie. the 'heavy spot' on top)- Reversed when the tire moves down (ie. 'heavy spot' on bottom):

    At the top: As the tire moves up, the bead does not. No longer guided by the tire wall it maintains its tangential velocity until it reestablishes contact at a new tire wall location, further from the imbalance.
    At the bottom: As the tire moves up, the bead is lifted with the tire and does not change its location in the tire wall.
    On a side between top and bottom: As the tire moves up, the bead rolls down the tire, changing its relative location in the tire wall further from the imbalance.
    Reduced Tire Oscillations: Each oscillation (tire movement, up and down) moves the beads progressively further from the imbalance ('heavy spot'), reducing the imbalance. Therefore, the tire becomes more balanced each oscillation until the tire is balanced.
    No Tire Vibration: The beads are held by centrifugal force in their balanced state. Because no imbalance exists, there are no vertical movements of the tire to disrupt their positions.
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  3. #3
    RaceTape Ninja Force McCocken's Avatar
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    Interesting.

    I'm sure tire a tire tech would love to see that spill all over the shop floor when the tires are unmounted. Just sayin'.
    Yer pal,
    Force

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    Sudden changes in balancing in a dynamic race environment may not be a good fit for this application. Especially if sudden changes perceptibly influence the handling when driving 10/10 (thinking hard decel, curb riding, etc)

    I believe this application is more suited (and somewhat more common) for vehicles with more constant velocity (like large truck wheels).

    No first hand experience here; I've always used traditional wheel weights, street and track.

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    Administrator ucfbrett's Avatar
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    So we have a simulation that uses a cordless drill and a water bottle, which isn't remotely shaped like a tire, nor does it have a center section like a wheel or a donut shape, like a tire, to say nothing of rpm. Then we have some guy with the clapped out prop car from "The Lincoln Lawyer" "testing" Dynabeads.

    I'll stick with wheel weights, good tires and competent tire shops.


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    You guys balance your tyres? Even our 135hp Swift spins the rim inside the tyre. Pointless exercise unless there's a really big vibration.

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    "Shoe" Stuntman's Avatar
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    Lots of racecars don't balance tires.

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    Administrator ucfbrett's Avatar
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    Quote Originally Posted by Stuntman View Post
    Lots of racecars don't balance tires.
    True, that. I was running tires for about a year that I thought the shop was balancing when I learned it was not. And I never knew.

  9. #9
    Senior Member bellwilliam's Avatar
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    you are all party poopers.....This is the racing secret sauce. Was gonna pass it onto Billy for next year's LeMan...
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    Quote Originally Posted by Stuntman View Post
    Lots of racecars don't balance tires.
    Billy, I know you're new to racing and haven't spent much time in race cars. When you're driving flat out like me you better have your damn tires balanced.
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    Race car drivers need big balls - not little ones.
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    We are fortunate to have our own tire machine and balancer. I rationalized this purchase about 10 years ago when I got tired of the inconvenience of taking tires to a shop, waiting, and paying and then to discover I had a less than perfect balance.

    We have a relatively inexpensive balancer - but I can assure you that we can balance as good or better than ANY shop with a mega-expensive balancer. The key is neither small balls or big balls (lol) but the utilization of a lug-centric plate kit. Almost all tire shops use a cone to try to center the rim on the balancer. Many wheels are manufactured in such a way that the surface the cone is engaged with (and the cone shape itself) are NOT conducive to achieving a true fit. The consequence is that you get a less than perfect balance.

    In comparison, we use a lug-centric system comprised of different plates and "fingers". Rims are clamped onto the balacer via ALL of their lug holes and held precisely in place - just as they are on the car. This system was popularized in the early 90's with the introduction of Lexus dealerships. Lexus insisted that EVERY dealership would utilize a lug-centric tire balancing system in order to insure that the Lexus car would maintain their extremely smooth ride.

    In racing, winning is a combination of numerous, minute advantages and I really believe that a well-balanced tire is an advantage. (Vibration is a wasted energy that you'd rather have helping to propel the car rather than working against it.)
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    Master of Disaster SteveLevin's Avatar
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    In truck/motorhome tires it seemed to work and there were those that swore by it (I had it in my front tires on the motorhome, and at speed they were smooth as glass, but I didn't have a lot of points of comparison).

    But that's almost the exact opposite of the racing environment. And I can tell you that the first few moments -- until you got to maybe 25mph -- I could feel the tiniest wobble in the front end (seemingly more when it was very cold), so I suspect in a race environment it'd suck pretty badly.

    Steve
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    Quote Originally Posted by CoolTech View Post
    We are fortunate to have our own tire machine and balancer. The key is the utilization of a lug-centric plate kit.
    In racing, winning is a combination of numerous, minute advantages and I really believe that a well-balanced tire is an advantage.
    I have a different set of experiences. I also own my own changer and balancer. IMO it is important to balance street tires because there is more weight at the tread for that 50,000mile durability. Even DOT-R Race tires weight nothing with thin tread easily damaged. Because of the light weight felt balance is insignificant even in the 150mph zone. I still balance new tires but won’t balance a flipped tire and you can’t feel a balance issue within a couple of laps as the soft rubber scrubs off. If wheel tire combos really need “balance” I would be looking into wheel runout. In my experience 2+oz of weight is about 015” out of round wheel. 040” out is about 3-4 oz . I have hydraulic tools and will bend back wheels once I get about 2oz of weight needed and get that back into the 1oz territory. I can feel about 020” out of round on track. Also, if a wheel is hubcentric there is no problem using a cone. The real problem is using an aftermarket wheel that was designed to be used with several bolt patterns and never designed to be hubcentric. Modern manufacture has blurred the line between hub and lug centric to the point this is really a non-issue. Mounting a wheel on a cone is not easy. It is actually a tricky job to do right and I have never seen a pro tire monkey impress me with their method. Also one who flips tires to get more life can very successfully balance the wheel only. Then mount race tires and drive and probably not feel any tire imbalance. The caveat to that is really heavy DotR tires that suck anyway like the Toyo R888 which seems weighs a ton. That had to be the worst tire I have ever tracked. I would rather have an old flipped hoosier A than a new R888.
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    All joking aside (sorry Billy, couldn’t resist), I do wonder how long the balance lasts, and how much it matters if any imbalance isn’t perceptible to the driver. Consider how much we burn down a set of tires in the course of competition, wear is appreciable even in a short qualifying stint - and not necessarily "even".

    I’ve had tires slip nearly 180 (rare) and was oblivious to it until I checked my crayon marks. I've thrown wheel weights (even after taping them). Neither is anything like an issue with the surface of the tire. We'll use flat spots and tire slag as an excuses. I've yet to hear anyone dream up wheel weights as an excuse.

    Having said all that, maybe the most worthwhile reason to balance wheels may not have anything to do with lap times. Inspection. There have been a couple occasions over the years where my tire guys spun up a wheel and spotted issues. In one instance I promptly tossed the wheel. Good reason to tip your tire people, and ask them to inspect the wheels every mount/balance. Of course you should be checking your wheels too but a second set of eyes doesn't hurt.

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    Senior Member fatbillybob's Avatar
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    Quote Originally Posted by SeanB View Post
    I do wonder how long the balance lasts, and how much it matters if any imbalance isn’t perceptible to the driver.
    I’ve had tires slip nearly 180 (rare) and was oblivious to it
    My limited understanding of racing from a crew chief perspective is setting up a car so the driver is confident to push the car to the limit is much more important than “how” the car is set up. So yeah, IMO imbalance matters if it effects the driver’s confidence and if you can show it in the laptimes. Tire slip is a preventable issue. I have never seen a case where it wasn’t.

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    Quote Originally Posted by SteveLevin View Post
    In truck/motorhome tires it seemed to work and there were those that swore by it (I had it in my front tires on the motorhome, and at speed they were smooth as glass, but I didn't have a lot of points of comparison).

    But that's almost the exact opposite of the racing environment. And I can tell you that the first few moments -- until you got to maybe 25mph -- I could feel the tiniest wobble in the front end (seemingly more when it was very cold), so I suspect in a race environment it'd suck pretty badly.

    Steve
    My trucks 35" tires would not balance, took all the weights off and tossed in a bag of beads; done deal.

    I had the thought of using it on track wheels but on the hoosiers you're always picking up marbles and changing tires every race weekend so idk if you'd see the benefit. I also never balance my race wheels.
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  18. #18
    Master of Disaster SteveLevin's Avatar
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    Quote Originally Posted by dc2696 View Post
    I had the thought of using it on track wheels but on the hoosiers you're always picking up marbles and changing tires every race weekend so idk if you'd see the benefit. I also never balance my race wheels.
    I'm not sure how you'd figure out the right weight, either. I recall Dynabeads was like 16oz of beads for a 22.5" wheel, but my entire tire+steelie for the motorhome weighed, literally, 130lbs. or so. So additional unsrpung weight wasn't a big deal

    Steve

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    Senior Member bellwilliam's Avatar
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    So 2 have tried it and worked (on truck tires) !!

    Steve: from my research. It is 10-13LB of tire/wheel weight per 1oz of BB
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